Field of the Invention
The present invention relates to a method of manufacturing a ceramic structure. More specifically, the present invention relates to a method of stably manufacturing a ceramic structure having high dimensional accuracy.
Description of the Related Art
Conventionally, ceramic structures have widely been used in, for example, catalyst carriers for purifying exhaust gas of cars, filters for removing diesel particulates, and heat storages for combustion devices. Many of ceramic structures use a honeycomb structure having a honeycomb shape including, for example, partition walls arranged in a lattice cross-section to define a plurality of cells extending from one end face to the other end face to serve as through channels for fluid. Such a honeycomb structure is manufactured by extruding a forming material (kneaded material) through a die (extrusion die) of an extrusion machine to form a ceramic formed body having a desired shape and treating the ceramic formed body in a drying step and a firing step.
The forming material that is extruded through the die to form the ceramic formed body is prepared by mixing raw materials consisting of ceramic particulates, a binder and the like, with a predetermined compounding ratio and then by kneading so as to be adjusted to have a viscosity suitable for extrusion. To adjust the viscosity, a liquid containing at least one of water, surfactant, lubricant and, plasticizer, for example, is added to the forming material.
More specifically, a batch-mixing device (batch mixer) is first used that performs dry-mixing (first mixing) of the inorganic raw materials and the binder to form a uniformly mixed dry mixture and then performs wet-mixing (second mixing) to mix the added liquid, such as water, and the dry mixture to form a wet mixture. The wet mixture is then loaded into a kneading machine and kneaded into a kneaded material and eventually become a forming material having an adjusted viscosity suitable for extrusion.
The manufacturing process includes a step of determining the amount of the liquid, such as water, added in the wet-mixing (or the amount of water content in the batch material), a step of measuring each temperature of a barrel and a screw of the extrusion machine, a step of measuring the rotational speed of the screw, and a step of measuring the extruded shape of the extruded body (corresponding to the ceramic formed body) just after being extruded through the extrusion die. The extruded body is manufactured in a manner stably keeping the extruded shape of the extruded body by adjusting the batch material, the barrel temperature, the screw temperature, the screw rotational speed, and such to keep the extruded shape of the extruded body within an acceptable range and to keep the dimensional accuracy of the extruded body (see Patent Document 1).
[Patent Document 1] JP-A-2013-545641